hissssss

[walshinator666]

First off everything I have are racks...that being said I have a loud noise problem here is how everything is hooked up...
guitar-->ch1 of decimator ch1 out-->in of rm4
parallel loop send-->ch2 of decimator ch2 out-->input of mfx out-->parallel loop return of rm4 post out of rm4 to input of rt2/50 than connect to randall mts 2x12 cab...I don't know if the decimator isn't working right or if it's hooked up wrong or what... any suggestions on how to hook it up or what ever you might think could be the problem.The noise is comming for the moduals maybe send the all in to get a noise switch put in...I don't know
thanks

 

[Mister Joshua]

Looks fine as far as hookup. I use a Rocktron MFX in the FX loop of my RM4 with the HUSH system (which is the exact same principle as the Decimator and should be identical) and have a noise free system.

I did however have a problem with one of my Salvation mods that made a huge amount of hiss. I had one built without a noise gate and it was hissing so bad i couldn't use it. Tony sent me a gate switch and upon installation solved the problem. So i would look into maybe getting noise gates in your modules.

Also you can try to put different modules in different places to see if that kills the hum. If it hums on all four channels regardless of what module you use (especially the cleans) then it is probably not your modules. If it only hisses on a particular module and the hiss follows as you plug it in to different slots then it is your module. Etc Etc...

Hope that is a good start to your troubleshooting bliss!

Peace, Joshua

 

[rhequiem]

Have you tried removing the Decimator from the chain? I haven't had any hissing problems with my RM4, so I'd be surprised if it's all of your modules. Do you have another power amp to try out? Perhaps you may have a defective tube somewhere in there, too...

 

[walshinator666]

thanks i'll give that a try.I have a blackface in 1st position no hossss,a modded jtm in 2nd no hisss a modded sl+ in 3rd lots of hisss and a ultra xl in 4th with lots of hissss'so i'm thinking it's the high gain moduals but I thought that the decimator was supposed to get rid of all noise.

 

[JKD]

The decimator should be running in series with the preamp signal, not parallel.

 

[walshinator666]

I'll try switching that as well but generally when i hook up in series it sounds like crap and much quieter.If anyone has a decimator do you know how the GND LIFT buttons should be set at i've got ch1 pressed out and both ch2 buttons pressed in.I don't even know what they are for.In is LIFT and out is GND by the way.

 

[JKD]

This is a rack mount decimator pro right and not a g-string?

 

[walshinator666]

decimator prorackG dual channel by ISP technologies...yes

 

[walshinator666]

O.K switching to the series loop took care of the hissss,but the volume is much lower ie in parallel i had volume set at around 8:00 on the rt2/50 in series a compariable volume is at around noon.That's just for playing with cd's but might not be loud enough for a live gig.It seems my sound is much more tweekable now though

 

[JKD]

The parallel loop would never kill the his correctly because you're mixing a signal wet/dry with the Effects control....hence the series loop works best

You could always try it inline between the pre-amp and the RT2/50 and see if it's any better

preamp out -> Dec ch in -> Dec Out -> RT2/50 in.


There was a comment from Bruce about the impedance / loading of the RT2/50 input but sadly I don't recall it exactly....something to do with input sensitivity but I don't think it bears on this situation as you're using the RM4 outs.

Also possible that the pre-amp tube driving the FX loop buffers on the pre-amp is shot and needs changing but sadly I can never remember which of the three it is.

 

[walshinator666]

I tried hooking it up the way you just suggested and the noise was back.It seems the way you suggested in the series loop is the best for me.Thanks for all your help,problem solved.